OpenMQTTGateway is, as the name suggests, a bi-directional gateway between MQTT and other hardware and/or protocols that may be running in or around your smart home. It supports most of the ESP8266 range of hardware, as well as an Arduino equipped with a Wiz W5100 ethernet adapter. The basic idea is that your ESP (or Arduino) interfaces with MQTT on the main network and provides seamless communications with (for instance) 433MHz or IR devices which otherwise are not directly connected.

A while back Florian made the package easily upgradeable by adding module support, where contributors can add support for other hardware and protocols by adding additional module files, rather than having to mess with the core functionality. This usually comes down to adding a single “ZgatewayXX.ino” or “ZsensorXX.ino” file (where “XX” is a unique identifier) and possibly an additional .h file, depending upon how complex your Z file is.

The latest addition is for a Bluetooth Low Energy based plant sensor (the Mi Flora) and provides a useful example of interfacing to BLE devices.

Browsing through the wiki pages on the ITEAD site is always a good way to pass a few idle minutes and usually rewards the curious reader with interesting stuff (like schematics, for instance) which ITEAD are kind enough to publish for our edification. Today’s snippet was some information on what looks like an as-yet unannounced product, a WiFi to 433MHz gateway module. The schematic shows this as an ESP8266-based unit, but there’s no separate flash memory chip that I can see and the block diagram refers to an ESP8285 (shame!). There are both transmitter and receiver sections on the 433MHz side and it appears to use an EFM8BB1 “Busy Bee” 8-bit microcontroller to interface between the 433MHz RX/TX section and the ESP UART, with what looks like a slide switch (S2 on the diagram) to disconnect the Busy Bee to allow for programming of the ESP. The device itself receives external power via a micro-USB socket.

Depending upon the price (and ITEAD prices are usually pretty reasonable) and the range of the 433MHz components, this could be a neat little device to have around. It’s not just all of those older 433MHz switch modules that have been available for years, but also the slew of devices which just transmit (doorbells, weather stations, window interlocks, etc). There does seem to be a four device limit on the number of remote 433MHz modules supported by the stock firmware though, according to the User’s Guide.

Update – ITEAD have just sent out a “Mid-Year Carnival Sale” promotion which features this unit (with the photo above) but, bizarrely for a sale, without a price.

Update 8th Aug 2017 – The main sales page is available on ITEAD’s site now and, for a time anyway, the unit is available at an introductory price of $9.90 (down from $12.90). There are some clarifications of the details too, with the supported device limits being shown as “up to sixteen 433MHz RF devices” or “up to four 1-4 button 433MHz RF Remotes” (so basically 16 addressable channels).

As expected, Theo isn’t far behind and Sonoff-TASMOTA has had support for the 433MHz RF Bridge incorporated since the 5.5.0 version (released on July 30th), with further updates to the code added in v5.5.1.